This invention is directed to a coupling for connecting a threaded rod to a second element having a bore provided therein and more specifically, to a coupling for quickly connecting the threaded push rod of an air motor to the clevis of a brake actuating lever and automatic slack adjustor on a vehicle assembly line without the need for any other tools.
More particularly, this invention is directed to a coupling for quickly connecting the threaded push rod of an air motor to the clevis of a brake actuating lever and automatic slack adjustor of the type disclosed in U.S. Pat. No. 3,949,840 which issued to J. C. Cumming, et al, on April 13, 1976. Such a device will hereinafter be referred to as a brake actuating lever which, for purposes of this invention, will be used to describe a brake actuating lever that includes an automatic slack adjusting mechanism as well as a brake actuating lever without an automatic slack adjusting mechanism. Other brake adjusting levers of the type with which the present invention may also be utilized are described in U.S. Pat. Nos. 3,507,369, 3,526,303, U.S. Pat. No. Re. 26,965, U.S. Pat. Nos. 3,121,478, 3,351,164 and 3,371,755.
The brake actuating levers which the present invention is particularly directed are utilized primarily in a rotary cam actuated internally expanding brake assembly. The brake actuating lever is splined at one end to a shaft which rotates the cam and the other end is connected by means of a clevis to the push rod of an air motor. Various connections have been used between the threaded push rod of the air motor and the clevis. In one conventional connection the threaded push rod is threaded into a tabbed bore provided in the clevis and upon adjustment to provide the proper length, a locknut is threaded down and seated tight against the surface of the clevis to prevent loosening of the push rod. This requires rotary movement of the push rod relative to the clevis or the clevis relative to the push rod and may require either removing the clevis from the brake actuating lever or the push rod from the air motor. Removal or disassembly of component parts, of course, requires whatever additional steps may be necessary to reassemble those parts at the point of installation on the vehicle assembly line.
One approach to avoid such disassembly has been to provide both a locknut and an externally threaded ferrule or yoke adaptor to the threaded push rod. During assembly the push rod is brought into juxtaposition with a threaded bore provided to the clevis. The yoke adaptor is threaded to the bore in the clevis and then the locknut is tightened against the yoke adaptor to prevent disassembly during service. This avoids the need to disassemble parts of the brake actuating lever or the air canister, but it still requires the use of tools in tightening two separate nut members in a relatively confined space on a vehicle assembly line.